Goal: This proposal requests support for a Mentored Clinical Scientist Award (K23) for Dr. David Rabago to develop research expertise in the empirical assessment of physical complementary and alternative medicine (CAM) therapies. Background: Prolotherapy (PrT) is a popular, growing, unregulated CAM therapy for chronic musculoskeletal pain in which an irritant solution is injected into painful ligaments and adjacent joint spaces. No methodologically rigorous clinical or basic science trials exist demonstrating the efficacy or limitations of PrT. Knee osteoarthritis (OA) is a common condition with high patient and societal burden; there is no cure, and patients are often refractory to care. Qualifications: Dr. Rabago has been the principle investigator (PI) on one RCT evaluating a CAM therapy, and is completing his National Research Service Award clinical research fellowship at the University of Wisconsin (UW) Department of Family Medicine (DFM). Environment: The DFM and UW Medical School are committed to Dr. Rabago's development as an independent clinician-scientist, as reflected in strong letters of support from the DFM chair, mentors, and collaborators. The UW is an ideal environment for the proposed work because it provides access to experts in the basic science of musculoskeletal injury, RCT methodology, PrT, CAM and Integrative Medicine. The UW also houses programs in Rehabilitation Medicine and Sports Medicine from which to recruit subjects. Training: Through coursework, seminars, and individual and group mentoring, Dr. Rabago will acquire advanced knowledge and skills in statistics, study design, research ethics, management/leadership, scientific writing, basic science animal-model experimentation and Integrative Medicine practice. Research: During this training grant, Dr. Rabago will be the PI on an RCT assessing the efficacy of PrT for OA knee pain. He will also be the co-PI on a series of animal model experiments to assess the healing response after PrT. Significance: If received, this K23 award will facilitate 1) Dr. Rabago's training to become a researcher able to independently assess CAM therapies and 2) the assessment of PrT, a significant CAM therapy for knee OA.